AUTHOR=Chandran Sarankumar , Pukalenthy Bharathi , Adhimoolam Karthikeyan , Manickam Dhasarathan , Sampathrajan Vellaikumar , Chocklingam Vanniarajan , Eswaran Kokiladevi , Arunachalam Kavithapushpam , Joikumar meetei Laishram , Rajasekaran Ravikesavan , Muthusamy Vignesh , Hossain Firoz , Natesan Senthil 

TITLE=Marker-Assisted Selection to Pyramid the Opaque-2 (O2) and β-Carotene (crtRB1) Genes in Maize

JOURNAL=Frontiers in Genetics

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2019.00859

DOI=10.3389/fgene.2019.00859

ISSN=1664-8021

ABSTRACT=<p>Maize is an excellent nutritional source and is consumed as a staple food in different parts of the world, including India. Developing a maize genotype with a combination of higher lysine and tryptophan, along with β-carotene, can help alleviate the problem of protein-energy malnutrition (PEM) and vitamin A deficiency (VAD). This study is aimed at improving lysine and tryptophan content by transferring <italic>opaque-2</italic> (<italic>o2</italic>) gene from donor HKI163 to β-<italic>carotene</italic>-rich inbred lines <italic>viz</italic>., UMI1200β<sup>+</sup> and UMI1230β<sup>+</sup>. For this purpose, F<sub>1</sub>, BC<sub>1</sub>F<sub>1</sub>, BC<sub>2</sub>F<sub>1</sub>, BC<sub>2</sub>F<sub>2</sub>, and BC<sub>2</sub>F<sub>3</sub> plants were developed using an o2 line HKI163 and two β-carotene-rich inbred lines, UMI1200β<sup>+</sup> and UMI1230β<sup>+</sup>, as the parents. Foreground selection using the associated marker umc1066 for the <italic>o2</italic> gene and the marker <italic>crtRB1</italic> 3′TE for the <italic>crtRB1</italic> gene was used to select the target genes. A total of 236 simple sequence repeat (SSR) markers distributed evenly across the maize genome were employed for the background selection. To fix the <italic>crtRB1</italic> allele in the BC<sub>1</sub>F<sub>1</sub> stage, individual plants homozygous at the <italic>crtRB1</italic> locus and heterozygous at the <italic>o2</italic> locus were selected and used for backcrossing to produce BC<sub>2</sub>F<sub>1</sub> plants. Furthermore, the selected heterozygous BC<sub>2</sub>F<sub>1</sub> plants from both crosses were selfed to obtain the BC<sub>2</sub>F<sub>2</sub> plants, which were then selected for the target gene and selfed to generate the BC<sub>2</sub>F<sub>3</sub> lines. From each cross, five improved lines with homozygous marker alleles for the <italic>crtRB1</italic> and <italic>o2</italic> genes with a recurrent parent genome (RPG) recovery ranging from 86.75 to 91.21% in UMI1200β<sup>+</sup>×HKI163 and 80.00 to 90.08% in UMI1230β<sup>+</sup>×HKI163 were identified. The improved lines had good agronomic performance and possessed high lysine (0.294–0.332%), tryptophan (0.073–0.081%), and β-<italic>carotene</italic> (6.12–7.38 µg/g) content. These improved lines can be used as genetic resources for maize improvement.</p>